Page 1224 - Small Animal Internal Medicine, 6th Edition

1196 PART X Joint Disorders

Because the clinical response to each NSAID varies between
dogs, it is reasonable to switch drugs when the response
VetBooks.ir to one drug is inadequate (Table 69.1). When switching
from one NSAID to another, a washout period of at least
3 days without NSAID administration is recommended to
prevent toxicity. In dogs that are intolerant of NSAIDs or
those that require further analgesia, oral tramadol (2-5 mg/
kg q8-12h), gabapentin (2.5-10 mg/kg oral [PO] q8-24h),
or amantadine (3-5 mg/kg PO q24h) can be helpful in
pain management.
Oral and injectable chondroprotective agents and
nutraceuticals may improve cartilage biosynthetic activity,
decrease synovial inflammation, and inhibit intra-articular
degradative enzymes. Oral glucosamine and chondroitin
sulfate can be administered separately or in combination.
FIG 69.1
Close-up mediolateral radiograph of left elbow joint of a An orally administered combination of glucosamine HCl,
14-month-old female German Shepherd dog with severe chondroitin sulfate, and manganese ascorbate has also been
degenerative changes secondary to a fragmented coronoid recommended (Cosequin RS [regular strength], 1-2 tablets
process. q24h in cats or small dogs; Cosequin DS [double strength],
2 to 4 tablets q24h in large dogs [Nutramax Labs, Edge-
wood, MD]). Polysulfated glycosaminoglycans (Adequan)
Medical treatment is symptomatic and nonspecific. or pentosan polysulfate may be beneficial when adminis-
Weight reduction may decrease the stresses acting on the tered intramuscularly (see Table 69.1). Hyaluronic acid is
joint. Rest often helps decrease the discomfort associated a nonsulfated glycosaminoglycan that can be administered
with acute exacerbations of disease. High-impact exercise, as an intra-articular injection to improve synovial viscos-
such as running and jumping, should be discouraged, ity and decrease inflammation. To achieve the maximum
whereas low-impact exercise done in moderation, such as theoretic benefit from all these products, they should be
swimming, leash walking, and walking on an underwater administered before DJD has occurred; therefore they
treadmill is recommended to maintain mobility and muscle may be indicated for treating dogs that have sustained
strength. Other forms of rehabilitation therapy may include trauma or undergone surgery known to have damaged
passive range-of-motion exercises, cryotherapy (ice com- articular cartilage. Clinical trials are necessary to evaluate
presses), muscle and joint massage, ultrasound, laser therapy, their efficacy.
and electrical stimulation. Dietary supplementation with
omega-3 polyunsaturated fatty acids (PUFAs), eicosapentae- FELINE OSTEOARTHRITIS
noic acid (EPA), and antioxidants (vitamin E, vitamin C, Cats are smaller and more agile than most dogs, and their
beta carotene, zinc, selenium) or feeding commercial “joint clinical manifestations of discomfort are often subtle. Clini-
diets” containing these supplements may decrease the cally significant DJD involving the elbow and hip joints is,
inflammation and pain of DJD. however, very common in aging cats. Signs include reduced
Pharmacologic therapies may be used to decrease further activity, decreased appetite, weight loss, irritability, and occa-
degradation of the articular cartilage, inhibit release of sionally lameness. Diagnosis is based on physical findings
inflammatory mediators, and control pain. The nonsteroidal and radiographic features. Treatment of DJD in cats is similar
antiinflammatory drugs (NSAIDs) are often recommended to that recommended in dogs and includes weight loss, reha-
because of their antiinflammatory and analgesic effects. The bilitation therapy, and administration of chondroprotective
primary action of most NSAIDs is reversible inhibition of medications, nutraceuticals, and analgesics. NSAIDs are
cyclooxygenase, preventing synthesis of the prostaglandins potentially more toxic in cats than in dogs due to deficient
responsible for pain and inflammation. Selective inhibi- glucuronidation pathways leading to a prolonged duration
tion of two forms of cyclooxygenase (COX-1 and COX-2) of effect so they should only be administered to normoten-
may explain some of the differences in efficacy and toxicity sive, normovolemic adult cats with no history of renal or
among the available NSAID agents. Preferential inhibition hepatic disease. Meloxicam has been shown to be safe and
of COX-2 with relative sparing of COX-1 by an NSAID effective when administered chronically to cats with DJD,
may be associated with improved control of inflammation and many cats have a good clinical response to very low
and decreased potential for gastric irritation and ulceration doses of meloxicam (0.1 mg/kg/day PO × 4 days, then
or renal toxicity. Renal function should be assessed before 0.1 mg/cat/day). Other commonly prescribed analgesic
prescribing any NSAID, after 7 days of treatment, and then at medications include buprenorphine (0.01-0.03 mg/kg bid to
least every 6 months during chronic administration. Owners tid via buccal mucosa), gabapentin (5-10 mg/kg bid-tid),
should also be instructed to monitor for inappetence, vomit- tramadol (2 mg/kg bid PO), and amantadine (3-5 mg/kg PO
ing, or melena, which could indicate gastrointestinal toxicity. q24h).